Gold nanoparticles are also used for drug delivery, as MRI contrast agents, and in solar cells.

For a study published in the journal Nanotoxicology,researchers tested the impact of nanoparticles in vitro on multiple types of cells, including adipose (fat) tissue, to determine whether their basic functions were disrupted when exposed to very low doses of nanoparticles.

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Subcutaneous adipose tissue acts as insulation from heat and cold, functions as a reserve of nutrients, and is found around internal organs for padding, in yellow bone marrow and in breast tissue.

The scientists discovered that the human adipose-derived stromal cells—a type of adult stem cells—were penetrated by the gold nanoparticles almost instantly and that the particles accumulated in the cells with no obvious pathway for elimination.

The presence of the particles disrupted multiple cell functions, including movement, replication (cell division), and collagen contraction—all processes that are essential in wound healing.

The most disturbing finding was that the particles interfered with genetic regulation, RNA expression and inhibited the ability to differentiate into mature adipocytes or fat cells.

“Reductions caused by gold nanoparticles can result in systemic changes to the body,” says Tatsiana Mironava, a visiting assistant professor in the department of chemical and molecular engineering at Stony Brook University.

“Since they have been considered inert and essentially harmless, it was assumed that pure gold nanoparticles would also be safe. Evidence to the contrary is beginning to emerge.”

This study is also the first to demonstrate the impact of nanoparticles on adult stem cells, which are the cells our body uses for continual organ regeneration.

It revealed that adipose derived stromal cells involved in regeneration of multiple organs, including skin, nerve, bone, and hair, ignored appropriate cues and failed to differentiate when exposed to nanoparticles. The presence of gold nanoparticles also reduced adiponectin, a protein involved in regulating glucose levels and fatty acid breakdown, which helps to regulate metabolism.

“We have learned that careful consideration and the choice of size, concentration and the duration of the clinical application of gold nanoparticles is warranted,” Mironava says. “The good news is that when the nanoparticles were removed, normal functions were eventually restored.”

“Nanotechnology is continuing to be at the cutting edge of science research and has opened new doors in energy and materials science,” says co-author Miriam Rafailovich, professor of materials science and engineering.

“Progress comes with social responsibility and ensuring that new technologies are environmentally sustainable. These results are very relevant to achieving these goals.”

The research, funded by the National Science Foundation, was a collaboration of Stony Brook University and New York State Stem Cell Science.